Issue  

A Multi-select control does not render inside a modal window when that modal is launched from a non-optimized (server-side rendered) table or grid. Instead of displaying the interactive control, the modal shows only the label or metadata of the Multi-select field, with no functional control present. 

Symptoms and Imact

• The Multi-select control is invisible or absent inside the modal — only its label or surrounding layout is rendered. 

• The issue is reproducible consistently when the modal is triggered by a row-click event on a non-optimized table. 

• When the parent table has Optimized code enabled, the Multi-select renders correctly in the modal. 

• Any configured OnChange actions on the Multi-select do not fire when the control is inside a non-templatized container. 

• Impact is limited to Traditional UI only — in Constellation architecture, multi-answer (Multi-select) controls are not supported at all. 

 Steps to Reproduce 

1. Create a section containing a Multi-select control mapped to a Page List or Multi-value property. 

2. Place that section inside a modal window configured as a Local Action. 

3. Add a Repeating Grid (table) to a harness or layout. Ensure the table's Optimize code option is not enabled (i.e. server-side rendering is active). 

4. Configure a row-click event on the table that opens the modal containing the Multi-select section. 

5. At runtime, click a table row to trigger the modal.  Result: The Multi-select control does not render — only the field label appears. No values can be selected. 

Root Cause   

The root cause is a templatized vs. non-templatized rendering conflict. The Multi-select control is a client-side templatized control — it relies on template-based rendering to initialize correctly. When a modal is launched from a non-optimized (server-side rendered) grid, the modal inherits the non-templatized rendering context of its parent container. In this context, the Multi-select control's client-side initialization routine is never invoked, so the control fails to appear.

Solution  

Enable the Optimize code option on the Repeating Grid that triggers the modal. This ensures the modal is rendered in a templatized context, allowing the Multi-select control to initialize and display correctly.  

This is documented in Configuring a modal dialog box for a list-based layout

References

Creating a table layout with code optimization 

Table layout 

Supported Actions for optimized tables 

FAQs about grid layouts based on templates  

Multiselect not working as expected in Pega 8.6.6 

Multi Select control is not working on Modal Dialog window Table - Pega v 8.4.4 

Modal dialog box 

Configuring a modal dialog box for a list-based layout 

Modifying presentation options of the non-optimized table layout 

Operations and actions in a table layout 

Multi-select does not work in a modal dialog 

Unable to launch local action within another local action 

Modal Dialog Closes on Mouse-Down event instead of Mouse-Up event 

Flow Actions configuration for editing rows in Embedded Data tables 

Views and Actions in modal dialog boxes